1. Field of the Invention
This invention relates to an image recording process using a light beam, and particularly a process of recording an image by scanning a recording material in two directions with a light beam such as laser beam.
More particularly, this invention relates to a method of adjusting the density of the entire image or portions thereof in a process of recording the image on a photosensitive material capable of halftone recording, for example a photographic film, by scanning the photosensitive material with a light beam.
2. Description of the Prior Art
Conventionally, to adjust the image density in the image recording process as described above, a density filter is inserted into the optical path of the light beam for the purpose of decreasing the image density. Alternatively, the level of the image signal is changed by use of an electric circuit.
Such conventional methods aim to change the intensity level of the light beam impinging upon the photosensitive material in order to adjust the image density. However, because of the non-linearity of the characteristic curve of the photosensitive material, it is extremely difficult to reproduce the desired gradation only by simply changing the intensity level of the light beam as in the conventional method. The conventional method using a density filter cannot compensate for the non-linearity of the characteristic curve of the photosensitive material. Thus, the conventional method of this type can change the image density only within the range of relative linearity of the characteristic curve of the photosensitive material. In the conventional method wherein an electric circuit is used to change the level of the image signal, a complicated control system is required to achieve non-linear intensity change so as to cope with the non-linearity of the characteristic curve of the photo-sensitive material.